Lightning Jump Algorithm Update

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C. Schultz, W. Petersen, L. Carey GLM Science Meeting 12/01/10. Lightning Jump Algorithm Update. Where we left you in ’09. Thunderstorm breakdown: North Alabama – 83 storms Washington D.C. – 2 storms Houston TX – 13 storms Dallas – 9 storms.
C. Schultz, W. Petersen, L. CareyGLM Science Meeting12/01/10Lightning Jump Algorithm UpdateWhere we left you in ’09Thunderstorm breakdown:North Alabama – 83 stormsWashington D.C. – 2 stormsHouston TX – 13 stormsDallas – 9 storms
  • Six separate lightning jump configurations tested
  • Case study expansion:
  • 107 T-storms analyzed
  • 38 severe
  • 69 non-severe
  • The “2σ” configuration yielded best results
  • POD beats NWS performance statistics (80-90%);
  • FAR even better i.e.,15% lower (Barnes et al. 2007)
  • Caveat: Large difference in sample sizes, more cases are needed to finalize result.
  • M.S. Thesis completed and study accepted to JAMC (Schultz, Petersen, Carey 2009); forms the conceptual basis of the lightning jump ATBD
  • Case Expansion
  • Since, we’ve expanded to 638 thunderstorms
  • Primarily from N. Alabama (537)
  • Also included
  • Washington D.C. (49 and counting)
  • Oklahoma (30 and counting)
  • STEPS (22)
  • Regional expansion has proven robust
  • POD: 82%, FAR 35%, avg. lead time: 22 mins.
  • DC LMA Results
  • 14 of 15 missed events by the 2σ algorithm were 1 tree knocked down
  • 64 severe events total for the DC sample.
  • Lightning jumps observed before almost every hail and tornado case
  • 1 tornado missed in entire sample (remnants of TS Nicole)
  • Skill Scores, 2σ, DC LMA region Example, tornadic storm July 16, 2007Proving the Utility of Total Lightning
  • Examined total and CG rates in 30 thunderstorms in four regions of country
  • Total lightning trends outperform CG lightning trends
  • Schultz et al., WAF, accepted, editing
  • Low topped/cold season and tropical environments
  • 40% of misses in these environments.
  • Can we still provide utility by tailoring algorithm?
  • Answer:
  • Tropical maybe, cold/low topped, tougher.
  • Time-height plot of reflectivity (top) and total flash rate (bot) for an EF-1 producing tornadic storm on March 25, 2010. Tornado touchdown time ~2240 UTC.Cold Season/Low Topped
  • Average peak flash rates:
  • Severe 11.53 flashes min-1, all have at least 1 flash
  • Non Severe: 6.60 flashes min-1
  • Some separation occurs at 6 flashes min-1
  • Landfalling Tropical Systems
  • Analyzed 8 landfalling TC’s within range of an LMA/LDAR
  • Average Peak Flash Rates
  • Severe: 6.60 flashes min-1, 5 storms w/o any flashes
  • w/o no flash storms, avg. flash rate 8.90 flashes min-1
  • Non Severe 6.35 flashes min-1
  • 0.29 flashes min-1 if non severe from Charley are removed
  • CharleySB CAPE18Z August 13, 20040-3 km Helicity18Z August 13, 2004No tornado, but increases in rotation observedTotal Flash Rate (flashes min-1)Total Flash Rate (flashes min-1)100 km from radarSB CAPE 18Z Sept. 25, 2005Purple line – total flash rate (flashes min-1)Contours - Merged Azimuthal Shear, Smith and Elmore (2004), using WDSS-II0-3 km Helicity 18Z Sept. 25, 2005100 km from radarOther “misses”
  • e.g., Feb 6, 2008 EF-4 tornado producing storm, 1117 UTC
  • Downward trend in total lightning masks any small pulses in electrical activity.
  • 230 severe408 non severeExamining Environments
  • Goal: Using commonly used environmental parameters to determine when total lightning will be of most use.
  • Other parameters; temp, theta, theta-e, RH, e,es, r,rvs, etc. Future Work
  • Incorporate other satellite/radar products
  • Have robust satellite dataset from GOES-O/P tests
  • In what capacity does high temporal satellite and total lightning information benefit nowcasting of storm growth and decay?
  • Reflectivity/rotation comparisons
  • Testing of algorithm in real-time this summer at Redstone and White Sands
  • Work the GLM lightning proxy along with the proxy in the cell tracking framework.
  • Related Search
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